Teams Channels are capable of receiving email as detailed in this post.
The screenshot above shows an email address for a Channel:
The email address assigned to a Channel does not belong to any domain that has been added to the Office 365 tenant. The domain used is @location.teams.ms, where @location is where my Teams tenant is hosted (uk.teams.ms).
The address starts with randomly generated text, followed by the Primary Domain of the Office 365 tenant.
Custom Email Addresses
It is not possible to add a custom email address to a Channel.
If you are looking to deliver mail to a Channel using an email address that belongs one of your domains, for example to use for inbound customer contact, the workaround is with email forwarding.
Here I create a Mail Contact using PowerShell, specifying the Channel address as the ExternalEmailAddress.
New-MailContact -Name "Teams Testing Forwarder" -ExternalEmailAddress "email@example.com"
Now I need to assign an email address from my domain to the Mail Contact. In Exchange Online this can only be done using PowerShell.
Set-MailContact -Identity "Teams Testing Forwarder" -EmailAddresses SMTP:firstname.lastname@example.org,TeamsTestForwarder@lemonbush.co.uk
In the example above, I prefix the Channel email address (the ExternalEmailAddress) with SMTP: as this should be the Primary SMTP Address, followed with the email address I want to assign from my domain.
Verify the email address has been added.
Get-MailContact -Identity "Teams Testing Forwarder" | fl EmailAddresses,ExternalEmailAddress
Mail can now be sent to the Channel using the email address added to the Mail Contact.
This is a workaround, it does not stop someone emailing the Channel address directly if they know what the actual email address of the Channel is.